| Detected brand | Visa |
| Digits | 16 |
The Luhn check only validates the number's structure — it cannot tell whether a card is real or active. Computed entirely in your browser; never store real card numbers here.
Check a card number with the Luhn algorithm, free. The Luhn algorithm (ISO/IEC 7812-1) is a simple checksum that detects accidental digit errors in identification numbers, including most credit/debit cards. This tool runs the Luhn check on a card number and detects the likely brand from its prefix and length — entirely in your browser, for testing and education only.
It runs the Luhn checksum and identifies the card brand, so you can spot mistyped numbers and generate/validate test data — it does NOT verify a real account. 100% free, no registration, and complete privacy — everything runs locally in your browser, so your data never touches a server.
Validates the number's check digit with the Luhn (mod-10) algorithm to catch single-digit typos and most transpositions.
Identifies the likely network (Visa, Mastercard, Amex, Discover…) from the prefix (IIN) and length.
The number is checked locally in your browser; nothing is uploaded, logged, or stored.
Unlimited checks with no account, on desktop and mobile.
No. Luhn only confirms the number is internally consistent (no obvious typo). It does NOT mean the card exists, is active, or has funds — only the issuer can confirm that. Use this for testing and validation UX, not fraud decisions.
A mod-10 checksum (ISO/IEC 7812): double every second digit from the right, subtract 9 from any result over 9, sum all digits, and a valid number has a total divisible by 10. It catches most single-digit errors and adjacent transpositions.
From the leading digits (the Issuer Identification Number) and the number's length — e.g. Visa starts with 4, Amex with 34/37 (15 digits), Mastercard in the 51–55 / 2221–2720 ranges.
No. The check happens entirely in your browser; the number you type never leaves your device. Still, only use test numbers here — never enter a real card you care about into any web tool.
No. This is a checksum and brand-detection utility for development and education. Real payment processing requires a PCI-compliant gateway.